Option to turn HTML escaping off

[adam-lynch]

I'd love this please.

My use case

I want to compile markdown for places where HTML isn't supported, just plain strings (like in Mac & Windows 8+ notifications for example).

I've already created a custom marked renderer which "cleans" markdown. So I try convert it to the nicest possible plaintext representation I can; i.e. it leaves some things pretty much as they are (like **strong**), it converts inline codespans to {code} (or {html} if code is passed), etc.

It works well but I just noticed that single quotes are being converted to '.

[adam-lynch]

I've gotten around it for now using the innerHTML, innerText trick to unescape HTML. Still would be a nice setting though.

[joshbruce]

#985